Certain voice communication systems currently exist, including push-to-talk (PTT) voice communication systems. With respect to PTT devices, current communication devices use out-of-band or voice sensing mechanisms to communicate control functions. Out-of-band approaches are used to prevent control signals from interfering with voice communication signals. The voice sensing approach senses the presence of a voice signal to generate the push-to-talk control signals. This voice sensing technique, however, often fails due to control signal timing issues, particularly when encryption units are included in the communication signal path.
Spread spectrum techniques have been used in communication systems. In spread spectrum systems, signal energy is first generated at a discrete frequency and then spread in time or frequency domains to establish secure communications, increase resistance to natural interference, and/or to prevent detection. With spread spectrum, a telecommunication signal is transmitted on a bandwidth considerably larger than the frequency content of the original information. Spread spectrum uses direct sequence, frequency hoping, or a combination of both techniques for multiple access and/or multiple functions to decrease potential interference to other receivers while maintaining privacy. These techniques can use pseudo-random number sequences as spreading codes. The pseudo-random sequences are sequences of numbers computed by a defined arithmetic process but are effectively random number sequences. Spread spectrum makes use of a sequential noise-like signal structure created by the use of spreading codes to spread the normally narrowband information signal over a relatively wideband band of frequencies. A receiver correlates the received signals to retrieve the original information signal.